Semicircle for nautical observations



(No Model). A O; M. HELLBERG.

semicircle for Nautical Observations.

No. 240,705. Patented April 26,1881.

WITNESSES: INVENTOR: Q56 W- JZAZ M'W BY *fl ATTORNEYS.

N. PETERS. PHDTD-LITHOGRAFNER. WASHINGTON. D. O,

ITE STATES 1 PATENT OFFICE- cHA'ELEs M. H'ELLB'ERG, OF JERSEY oI'rY, NEWJEEsEY.

SEMICIRCLE FOR NAUTICAL OBSERVATIONS.

SPECIFICATION forming part of Letters Patent No. 240,705, dated April26, 14881,

Application filed October 15, 1880. (No model.)

To all whom it may concern:

Be it known that I, CHARLES M. HELL- BERG, of Jersey City, in the countyof Endson and State of New Jersey, have invented a new and ImprovedSemioircle for Making Angular Measurements, of which the following is aspecification.

The object of this invention is to provide an improved instrument fortaking observations at sea, either at day or night, to determine theships position.

The invention consists of a frame having an arc of one hundred andeighty degrees,suitably and adjustably mounted, in combination with aday and night binocular telescope and reflecting-glasses, saidinstrument being designed as a substitute for the ordinary sextant orquadrant.

Figure 1 is a perspective View of the device. Fig. 2 is a plan of thesame, partly in section, and with parts broken" away to exhibit otherparts. Fig. 3 is a sectional side elevation of the same.

Similar letters of reference indicate corresponding parts.

The quadrant and sextant in common use are of but little or no serviceat night, especially on a dark night, because they are provided withnon-magnifying object-glasses and glasses. of small aperture. Henceinhigh latitudes in winter, when the sun cannot be seen for days, theordinary sextant is of no value to the navigator.

The improved instrument consists of a suitable hollow case, A,preferably of ellipsoidal cross-section for the sake of strength,provided. with end strengthenin gencirclin g ribs, a a, and havingsockets or openings 1) b made through it for the reception and freemovement of the semicircular frame B, which consists of an are, c, ofone hundred and eighty degrees, graduated in the usual manner withsextants, as shown at c, and having a toothed periphery, as shown at cl,for the engagement of the thumb-wheel G, that is journaled in a hanger,G, which depends from the under side of the case A. The frame B servesthe same purpose as the arc in the ordinary sextant or quadrant, beinglengthened into an arc of one hundred and eighty degrees for better ada-ptation to the case A and telescope I. Said semicircular frame B isalso provided with radial strengthening-braces ff, that converge to acentral point. Fixed on the lower part of the brace f, and extending atright angles from either side thereof, is a reflector, D, that isdesigned to receive the rays of light from the observed object. mountedor pivoted so as to move in a vertical plane on a horizontal pin, g,that is supported in the lugs h h, which project upward from the top ofthe case A at the front thereof.

Bi gidl y secured on the top of the case A is a vernier, E, tofacilitate the reading of the are c.

A straight forward arm or extension, F, from the bottom of the case A,supports on its outer end a reflector or horizon-glass, G, which isdesigned to receive the reflection from the reflector D.

Within the front end of the caseAis an annular groove, 1, within whichis fitted a colored glass, H, to prevent the rays of light reflectedfrom the horizon-glass reflector G into the binocular telescope I frominjuring the eyes of the operator. Said glass His preferably set inplace through a slot, 12, made for that purpose in the side of the caseA 5 but it may be placed and held in position in any other well-knownmanner. The telescope I resembles an ordinary opera or field glass ofgood magnifying powers, and of large apertures for service as anight-glass, and it is set in the case A'so that it can be readilyremoved and used simply as a' telescope.

In taking an observation with this simi-circle the operator can use botheyes, and thus employ the full strength of his sight, and can Saidsemicircular frame B is see farther and more clearly than with theordinary sextant-glass. The horizon can be clearly seen by the operatorlooking through the telescope I, even behind thehorizon-glass G.

This instrument can be used without night and day glassesin the samemanner as the ordinary quadrant. It is intended chiefly for nightobservations.

The eye-plateK is provided with two minute orifices, m m, and hinged orpivoted, as shown, to the rear end of the case A. Lookingthrough theorifices mm, when the telescope is removed and the eye-plate K isclosed, the operator can take a good observation in a clear day.

I do not confine myself to the use of the thumb-wheel O for moving theframe B, as obviously other and well-known devices may be used for thispurpose, the wheel 0 being herein shown to indicate a manner ofadjusting said frame B.

Having thus fully described my invention,I claim as new and desire tosecure by Letters Patent 1. An improved semicircle for making angularmeasurements, constructed substantially as herein shown and described,consisting of case A, pivoted semicircular graduated frame 13,, VernierE, reflectors D G, and binocular telescope I, operated as set forth.

2. In a binocular instrument for making angular measurements, thecombination, with a pivoted adjustable semicircle,B,provided with agraduated arc, c, of the fixed vernier E, sub stantially as and for thepurpose described.

CHARLES M. HELLBERG.

Witnesses:

I. I. STORER, (J. SEDGwIoK.

